Self-locking nuts of the internally threaded type have been in use for many years as illustrated in U.S. Pat. Nos. 1,726,628 issued Sept. 3, 1929 to T. G. Rennerfelt and 2,450,694 issued Oct. 5, 1949 to J. A. Sauer.
In self-locking nuts of this type, a metallic body is formed with an internally threaded cylindrical body cavity in which cavity is placed an annular cushion of elastic material that provides locking engagement with mating parts. This type of fastening device has proven to be very effective over the years in the use thereof in many different applications.